body {
    padding: 0;
    margin: 0;
    background-color: yellowgreen;
}

.div1 {
    height: 200px;
    width: 200px;
    position: absolute;
    left: 50%;
    top: 50%;
    background-color: white;
}

.div2 {
    background-color: black;
    height: 100px;
    width: 100px;
    position: absolute;
    left: 20%;
    top: 20%;
}